RUNX1 and leukemia: MIB1 encodes for an E3 ubiquitin-protein ligase that is involved in, among other processes, NOTCH signaling and ubiquitination of centriolar satellites.51,52 The MIB1 gene locus has been shown to be hypomethylated in ETV6::RUNX1+ BCP-ALL53,54 and is highly expressed in ETV6::RUNX1 leukemia compared with other subtypes (MILE study, St.